1. Field of the Invention
The present invention relates to an apparatus for loading a cassette containing therein a plurality of recording sheets at a predetermined position in a sheet feeding portion of a business machine such as an electrophotographic copying apparatus, an offset printer to which the principle of the electrophotography is applied, or the like apparatus.
The present invention resides in an apparatus for loading a cassette containing therein a plurality of recording sheets, comprising an actuator lever having an end portion pivotally mounted on a frame of the apparatus, a micro-switch for detecting the sheet having an actuator disposed at an operative position within a space for receiving the cassette so as to be engageable with the sheet contained in the cassette, connecting mechanism for connecting the lever and the micro-switch to each other in such manner that the actuator of the micro-switch is displaced to an inoperative position exteriorly of the cassette receiving space from the operative position within the cassette receiving space when the other end of the lever is moved to the inoperative position, a cassette lock member capable of projecting into the cassette receiving space at an operative position, a connecting mechanism for connecting the lever and the lock member to each other in such manner that the lock member is displaced from the operative position within the cassette receiving space to an inoperative position exteriorly of the cassette receiving space when the other end of the lever is moved to the inoperative position thereof, sheet lifting means capable of projecting to an operative position within the cassette receiving space, and connecting means for connecting the sheet lifting means and the lever in such manner that the sheet lifting means is displaced from the operative position within the cassette receiving space to an inoperative position exteriorly of the cassette receiving space when the other end of the lever is moved to the inoperative position.
2. Description of the Prior Art
As is well known, a cassette containing a number of recording sheets is widely used in most copying apparatus. The use of a cassette which is adapted to be removably loaded in the copying apparatus brings about a great advantage in that replacement of the recording sheets of one size by those of other sizes can be easily carried out by merely exchanging the corresponding cassettes with each other. In order to have a better understanding of the invention, a brief view will be made on the recording sheet feeding system and the structure of the cassette which have been hitherto known. The sheet feeding system may be classified as follows:
(a) A sheet feeding roller is provided at the copying apparatus in such position that the feeding roller can be brought into engagement with the uppermost sheet of the stacked recording sheets, while the feeding roller is mounted to be vertically movable. The feeding roller is rotated in proper timing relation with the copying process thereby to feed out the recording paper sheet by sheet. Decrease in the number of the stacked sheets is followed by the progressive lowering of the feeding roller so that the last or lowermost sheet in the stack can be fed out.
(b) The feeding roller is mounted stationarily at a predetermined position of the copying apparatus. The feeding engagement between the roller and a stack of the recording sheets is attained by a lifting mechanism disposed below the stack of the recording sheets to exert a pressure to press the stacked sheets toward the feeding roller so that the last or lowermost recording sheet can be fed out to the copying apparatus.
As will be apparent from the description above, the starting position of the recording sheet to be fed out will be progressively varied in the case of the feeding system (a), while in the case of the feeding system (b) the recording sheet can be fed out always from the predetermined position. As will be described hereinafter in more detail, in the case of the conventional copying apparatus, the image position on the intermediate medium (which may be constituted by a rotatable drum having a photo-electrically conductive layer in the case of the electrophotographic copying machine or by a negative plate or an original negative in the case of the offset printer) has to be aligned with the recording sheet in a perdetermined relation. Accordingly, the feeding system (b) is adopted more widely than the feeding system (a), because the former is less susceptible to any undesirable deviations in positional relationship between the image position and the position of the recording sheet. Of course, in the case of the feeding system (a), there are known synchronizing means for attaining the positional alignment between the image to be transferred and the recording sheet.
Next, hitherto known structure of the cassette will be briefly described in junction with the cassette loading apparatus. An example of a cassette intended to be used in combination with the feeding system (a) described above is disclosed in Japanese Patent Publication No. 26847/1974 (refer to FIG. 2, in particular). According to the teachings of this prior application, a sheet supporting plate is loosely placed in the cassette for supporting a number of the recording sheets thereon while an aperture is formed in the bottom wall of the cassette. For loading the cassette into a copying apparatus, the sheet feeding roller is first held at a position not to be in contact with the uppermost recording sheet of the sheet stack contained in the cassette, and thereafter the cassette is fixedly positioned in the cassette receiving portion of the copying apparatus with the aid of a projection provided at the cassette receiving portion and adapted to engage in the aperture formed in the bottom wall of the cassette. In addition to the positioning function, the projection serves for supporting the sheet supporting plate inserted in the cassette so that the lowermost recording sheet of the sheet stack within the cassette lies constantly at a predetermined position.
A typical example of a hitherto known cassette to be used in combination with the feeding system (b) described above is disclosed in Japanese Laid-Open Patent Application No. 127632/1974 (refer to FIG. 2). According to the disclosure, the sheet supporting plate is loosely provided in the cassette bottom so as to be rotatable about an end thereof (the end positioned remote from the sheet feeding roller) while a spring is interposed between the sheet supporting plate and the bottom of the cassette at the position immediately below the sheet feeding roller. Another example of a hitherto known cassette is disclosed in Japanese Laid-Open Patent Application No. 131139/1974 (refer to FIG. 3, in particular). As in the case of the just above mentioned example, a sheet supporting plate is provided and the feeding engagement between the sheet stack and the feeding roller is accomplished by a pressing member which is adapted to bear on the lower surface of the sheet supporting plate through a corresponding aperture formed in the bottom of the cassette under the influence of a spring force.
A similar combination as that of the invention is disclosed in the above-cited Laid-Open Patent Application No. 131139/1974. However, in the case of this prior art, the step for fixedly locating the cassette in the cassette receiving portion of the copying apparatus is separated from the step applying the pressing action onto the stack of the recording sheets. More specifically, when the cassette is to be loaded, a lever associated with the pressing member is manually manipulated to retract the pressing member from the plane on which the cassette is slidably moved, and then the cassette is positioned at a predetermined position in the cassette receiving portion of the copying apparatus. Thereafter, by manipulating the lever in the reverse direction, the pressing member is caused to contact with the stack of the recording sheets. In other words, two different manipulations are required for loading the cassette to the ready position for effecting the copying process, which is of course troublesome.